Control system for aircraft turbosuperchargers



May 15, 1945. M. A. EDWARDS ET AL CONTROL SYSTEM FOR AIRCRAFTTURBOSUPERCHARGERS Filed April l, 1943 2 Sheets-Sheet 1 .l LwoobammITM/enters: Martin A. Edwards,

Martin Lev'me', by WwW/ Then` Attorney.'

May 15, 1945.

Filed April l, 1943 l 2 sheets-sheet 2 59 i2 48 n J '5o V- inventors:

Martin A. Edwards,

Martin Levine,

by /WJWM Thei` Attorney.

` Patented May 15, 19.45 I

CONTROL SYSTEM FOR AIRCRAFT f TURBOSUPERCHARGERS f MartinA. Edwards,Scotia, and Martin Levine,

Schenectady, N. Y., assignors to General Electric Company, a corporationof New York Application April 1, 1943', serial No. 481,446

' (c1. 23o-11) l f 12 Claims.

Our invention relates to a control system for aircraftturbosuperchargers, and especially to control systems forturbosuperchargers wherein the turbosupercharger is operated by exhaustgases fom an aircraft internal combustion engine and the air compressedby the turbosuperchargers is used to supercharge the engine.Specifically, our invention is an improvement on the control systemdisclosed and claimed in the application of David R. Shoults, Serial No.452,294, filed July 25, 1942, and assigned to the same assignee asthepresent application.

An object of our invention is to provide a new and improved controlsystem for turbosuperchargers for aircraft.

Another object of our invention is to provide regulating means for aturbosupercharger which maintains constant a predetermined pressureappurtenant to the operation of the supercharger such, for example, asintake manifold pressure or carburetor intake pressure and, furthermore,to maintain this pressure over a predetermined range of operation withgreat stability.

Still another object of our invention is to providenew and improvedmeans for regulating a turbosupercharger in which constant carburetorinlet pressure is maintained over a predetermined range of operation,and thereafter substantially constant turbosupercharger speed ismaintained.

Further objects and advantages of our invention will become apparent asthe following description proceeds, and the features of novelty whichcharacterize our invention will be pointed out with particularity in theclaims annexed to and forming a part of this specication.

For a better understanding of our invention, reference may be` had tothe accompanying drawings in which Fig. 1 is a diagrammatic view of aturbosupercharger control system embodying our invention, and Fig. 2 isa diagrammatic view of a portion of Fig. 1 illustrating a modificationof Vour invention.

Referring now to Fig. 1 of the drawings, I0

indicates an aircraft internal combustion engine having an intakemanifold, not shown, and an exhaust manifold,'0nly a portion of which isvI6 and the compressor atIl. VConnected with the nozzle box I4 is awaste gate conduit I8 in stream of the .aircraft to the compressor. .To

which is located adjustable valve means gr waste gate I9 used inregulating the turbosupercharger. On the shaft of waste gate or valvevI9 is fixed an arm for use in positioning'thevalve.

Connected to the inlet of compressor I1 isan intake conduit 2| forconveying air from the slip this end conduit 2| is connected with asuitable ram 22 which faces into the slip stream of the aircraft. Thedischarge side ofcompressor Il is connected by a conduit 23 to theintake shown at II. A carburetor I2 is schematically of carburetor I2.If desired, a suitable intercooler, such as is indicated at 24, may beprovided in conduit 23 to maintain the temperature of the air enteringcarburetor I2 within a predetermined range for bestairplane performance.

The arrangement so far described is a known one and is to be taken astypical of any'turbosupercharger installation. In operation, exhaustgases from the aircraft engine are supplied through exhaust manifold I Ianda suitable conduit, if this is necessary, to the nozzle box I4 fromwhich they are discharged through a ring of nozzles to the turbine wheelI 6 of turbo'supercharger l5, or through waste conduit. I8 directly tothe atmosphere. When waste gate I9 is wide open, substantially all theexhaust gases discharge directly to atmosphere, little if any passingthrough the nozzles to the turbine wheel I6. This represents no load onthe supercharger. As waste gate I9 is gradually closed, pressure isbuilt up in nozzle box I4 effecting a grad-- ually increasing flow ofexhaust vgases through the nozzles to the turbine wheel to operate thesupercharger. Maximum load on the supercharger is reached when wastegate I9 is fully closed so that all gases from the engine are dischargedagainst the turbine wheel I6. Ordinarily waste gate I9 is in anintermediate position, part of the exhaust gases being discharged toatmosphere and the remainder passing through the turbine wheel I6. "l

Our invention has to do particularly with an improved means forregulating waste gate I9.

'Ihe position of Waste gate I9 may be varied by any suitable means, suchfor example as a hydraulic piston or the like. However, due to the very'low temperatures encountered by high flying aircraft the oi-l used toloperate a piston or similar means is likely to congeal andunsatisfactory operation result. Preferably, therefore,

we control the position of waste gate I9 through operation of meanscomprising an electric motor 25 of the split series field type havingeld windings 25a and 25h. Upon proper energization of motor 25, it will,as desired, rotate in either direction. The shaft 26 of motor 25 isconnected through a suitable clutch brake generally indicated at 21,gearing 29, shaft 30, crank 3| and,

linkage 32 to arm 20 controlling the position of waste gate I9. Theclutch brake 21 which broadly constitutes an electro-magnet comprises anelectrical winding 33 which, when energized, produces a magnetic field,causing longitudinal movement of a shaft 34 and a member 35 of magneticmaterial to engage with a cooperating member 36 of magnetic material onshaft 26 whereupon motor 25 drives gearing 29and consequently alsopositions wastegate I9. The members 35, 36 have adjacent frictionsurfaces whereby upon engagement rotation of one member causes rotationof the other. Upon deenergization of winding 33 a suitable spring means31 causes shaft 34 to move away from shaft 26 and, furthermore, causesmember 35 to engage against a stationary braking member 38, therebyquickly stopping waste gate I9 in the desired position and permittingmotor 25 to continue to rotate until its .kinetic energy is dissipated.The positioning of waste gate I9 is thereby accurately controlled sincethe brake portion of clutch brake 21 operates immediately upondeenergization of winding 33.

The operation of motor 25 and, consequently, the position of waste gateI9 may be controlled, as will be obvious from the following description,in response to any pressure appurtenant to an operating condition of thesupercharger I5.- It has been found desirable to maintain this pressureconstant for normal operation of the aircraft. This means that as theaircraft rises the speed of the supercharger must increase to maintainthis pressure constant. When a predetermined critical speed is reachedit is not feasible to permit further increase in speed of thesupercharger to maintain constant the pressure being regulated.Furthermore it has been found desirable to regulate the speed of thesupercharger and maintain it constant at the critical speed foraltitudes above the so-called critical altitude which is the altitude atwhich the maximum desirable supercharger speed to maintain constant apredetermined pressure is attained. In order to operate motor 25 andsolenoid-operated clutch brake 21 so as properly to position waste gateI9 to maintain constant a predetermined pressure appurtenantto anoperating condition of the aircraft engine IIJ or supercharger I up to acertain critical speed and thereafter to maintain constant this criticalspeed, or at least not permit it to be exceeded, we provide a regulatingmeans generally indicated at 39. Although it should be understood thatthe pressure to be regulated may be any pressure appurtenant to theoperation of supercharger I5, we have chosen by way of example toillustrate our invention as regulating compressor discharge orcarburetor inlet pressure. Accordingly the carburetor inlet pressure inconduit 23 is connected by means of a conduit 4D with the pressureresponsive means illustrated as a flexible bellows 4I of regulatingmeans 39.

It has been found that at high altitudes in the rareiied atmospherefound there, relays, switching devices andthe like may not operatesatisfactorily due to severe arcing and the' like which arcing would notoccur at atmospheric pressures. To eliminate any undesirable arcing ofthe relays and switching devices of regulating means 39 We 75 liaveprovided a sealed box or housing 42 within which is mountedsubstantially all of regulating means 39. Conduit 40 is connected tosealed box 42 as indicated so that the pressure in box 42 is carburetorinlet or compressor discharge pressure. The exterior of bellows 4I,which is fastened to. one of the walls of box 42, is subjected to thispressure and the interior of bellows 4I is evacuated so that movement ofbellows 4I will be in response to absolute carburetor inlet orcompressor discharge pressure.

The movement of the evacuate bellows 4I is opposed by a tension spring,generally indicated at 43, which is connected to bellows 4I through aconnecting link 44. The tension of spring 43 and consequently thepressure to be regulated may be controlled manually from the aircraftcabin 45 by means of a manual control rod 46 which is connected tospring 43 by means entering the sealed box 42 through a suitablestufling box or the like such as is shown at 41. Any change in thepressure within pressurized box 42 will cause the bellows 4I to expandor contract and move a contact-controlling arm 48 pivotally mounted at49 and connected to link 44 as indicated at 50. For conditions ofequilibrium the tension of spring 43 must be equal to the area ofbellows 4I multiplied by the pressure in sealed box 42. This pressureis, as was mentioned above, the quantity to be regulated which has beenillustrated by way of example as the carburetor inlet or thecompressorvdischarge pressure. If the pressure in sealed box 42increases, the force on the bellowsarea is greater than the tension ofspring 43 so that the bellows 4I is compressed. If, on the other hand,the pressure in sealed box 42 decreases, the force on the bellows areais less than the spring tension so that the bellows is extended. Thismotion of bellows 4I is made to control waste gate I9 in order tocorrect for pressure changes through the operation ofcontact-controlling arm 48.

Contact-controlling arm 48 is arranged to engage contacts 5l or 52 whichare connected in series with field windings 25b and 25a respectively-`of waste gate motor 25. The winding 33 of clutch brake 21 has been shownas serially arranged with splitl field winding 25a and 25h so thatWhenever either of these field windings is energized, winding 33 is alsoenergized. When contact-controlling member or arm 48 engages contact 5Iwhich is the waste gate opening contact winding 33 of clutch brake 21and winding 25h of motor 25 are energized. This particular energizationwill tend to rotate shaft 26 of motor 25 so as to open waste gate I9,thereby decreasing the speed of turbosupercharger I5 and consequentlydecreasing the pressure in sealed box 42. Similarly, ifcontact-controlling arm 48 engages waste gate closing contact 52,winding 33 of clutch brake 21 and field winding 25a of motor 25 areenergized so that waste gate I9 may be moved to tend to further closewaste conduit I8.

In order to prevent overtravel of the waste gate I9, we have providedsuitable limit switches serially arranged with the windings 25a and 25hof motor 25 as well as in series with motor 25 and the winding 33 ofclutch brake 21. As indicated in the drawings, limit switch 53 isillustrated as connected in series with series eld 25a while limitswitch 54 is illustrated as connected in series with series eld 25h. v norder to open limit switch 53 when the waste gate I9 reaches its fullyclosed position, we provide a member 55 mounted on shaft 30 whichengages limit switch 53 and moves it to the open position. Member 55also moves limit switch 54 to the open position when waste gate I9reaches its fully open position. Limit switches 53 and 54, therefore,prevent overtravel of waste gate I9 and furthermore control the totalwaste gate travel. It should be understood that these limit switcheswhich have been illustrated as being arranged outside of pressurizedblox 42 could equally well be contained within box 42 so as to preventundesirable arcing at high temperatures.

To stabilize the operation of regulating means 39 we provide ananti-hunting means in the form ,of a follow-upfsystem which includes apivotally mounted insulating arm 56 contained within pressurized box 42.Insulating arm 56, which is pivotally mounted at' 51, is illustrated assuitably supporting contacts 5I and 52 which, as was mentioned above,may be adjustably mounted thereon. Member 56, pivotally mounted at 51,is

moved in response to wastegate position by any means such as a crank orthe like. As illustrated in the drawings, this means comprises a crank58 mounted on a shaft 59 which in turn is `operated by a crank 60connected to shaft 30 which positions waste gate I9 by means of anoperating rod 6I and a crank 62. It will be obvious that with thisarrangement a follow-up mechanism is provided which is operated inresponse to the waste gate position. The movement of the contacts 5I and52 between full open and full closed positions of the waste gate valvedetermines the amount of droop in the regulator while the distancebetween contacts 5I and 52 determines the sensitivity of the regulator.This follow-up mechanism causes a permanent recalibration of pressurewith altitude, the magnitude of which depends upon the waste gate motionandthe total amount of droop required for stability.. l

Whenthe aircraft attains the critical altitude, which may be in theneighborhood of 25,000 feet, the speed of supercharger I5 has increasedto a value above which it is not feasible to operate it for other thanvery short periods of time. It is, therefore, desirable to provide meansfor preventing the speed of the supercharger fromv exceeding thisso-called critical' speed, andvtherefore for altitudes above thecritical altitude of supercharger I5 we have provided means for reg'-ulating the supercharger to maintain substantially constant speed. Tothis endlwe provide a suitable centrifugal governor generally indicatedat 63 which may be suitably driven from the supercharger so as to beresponsive to the speed ofthe supercharger. Governor 63 is adapted tomove a contact-controlling arm 64 which is normally biased against astationary contact 65 as by means of a spring 66. As the speed of thesupercharger reaches the critical speed, governor 63 will movecontact-controlling arm 64 away from contact 65 and as this speedincreases contact-controlling arm 64 engages a contact 61.

Contacts 65 and 61 are connected in a control circuit which will bedescribed hereinafter for controlling cont'act-controlling arm 48 tomaintain constant the speed of the super/charger above the criticalaltitude of the aircraft.

In order to utilize the opening and closing of contacts 65 and 61 tomaintain constant the speed of supercharger I5 above the critical speedby controlling contact-controlling arm 48 in a manner similar to thecontrol exercised on arm-48 by bellows 4I at' altitudes below thecritical altitude, we provide a restoring motor 68 of the direct currentsplit series field type having field windings 68a and 68h respectively.Contact 65 controlled by governer 63 is connected in series with a limitswitch 69 and with field winding 68a of motor 68 as well as in serieswith the armature of this motor. Similarly, contact 61 is connected inseries with a limt switch 10 and in series with a field winding 68h ofmotor 68 as well as in series with the armature of this motor. 'Motor 68is adapted to drive through suitable gearing 1I and shaft 12 a screw 13for raising and lowering a member 14 which supports the pivot 48 ofcontactcontrolling arm 48. The member 14 is provided with extensions14aand 14b respectively which are adapted to engage vlimit switches 69 and10 in the extreme upper and lower positions, respectively, of member 14.Below the critical altitude of the supercharger, governor 63 is in theposition indicated in the drawings and does not engagecontact-controlling arm 64- so that spring 66 maintains contact 65 inthe closed position, thereby with the member 14 in a position slightlyraised from that in the drawings energizing the eld winding 68a ofseries motor 68 through limit switch 69 to move member 14 to its extremelower position so that limit switch 69 is opened. This is the positionindicated in the drawings and below critical altitude pivot 49 is fixedlin this position so that contact-controlling arm 48 is controlled solelyby bellows 4I.

The expansion of bellows 4I is limited by a suitable stop 15 mounted inthe sealed or pressurized box 42 whichengages with a cooperating stopmember 16 pivotally mounted at 11 and connected to link 44 as indicatedat 18. Whenpthe aircraft goes above the critcial altitudefrstop member16 engages stop 15 so that thereafter contact-controlling arm 48 pivotsabout pivot 50 and is moved upwardly and downwardly Iby restoring motor68.

It will be obvious that the follow-up mechanism used for stabilityoperation and described in connection with the pressure-regulating meansabove operates in exactly the same manner for overspeed control that isabove the critical altitude as it does when regulating pressure belowthe critical altitude. It requires that the restoring motor 68 holds aslightly different speed with the waste gate wide open than it does withthe waste gate closed. This should cause no diiliculty, however, sincethe waste gate goes through a very small angle when holding constant thespeed of supercharger I5 between the critical altitude and higheraltitudes attained by the aircraft.

The operation of the turbosupercharger regulator described will beobvious from the detailed description made above. Assume that theaircraft is in the air and is flying at an altitude lower than thecritical altitude of the supercharger, that is, at an altitude below themaximum for which the supercharger I 5 is capable of maintaining,without excess speed a predetermined y pressure on the discharge side ofcompressor I1,

for example sea level pressure. Assume also that at such altitude wastegate I9 is'in a partially closed position, as indicated in thedrawings,4

creasing the tension on spring 43 and consequently requiring an increaseof pressure in box 42 before equalization of forces exerted by spring 43and bellows 4I is obtained,'contact-controlling arm 48 will lbe moved soas to engage the closing waste gate contact 52 with the consequentenergization of eld winding 25a of Waste gate motor 25 as Well asenergization of the armatureof this motor and also of the winding 33 ofclutch brake 2l. Such energization will cause shaft 38 to rotate in adirection to close waste gate I9, thereby causing more of the exhaustgases from the aircraft engine I to pass through the nozzles of turbinewheel I8 with the consequent increase in speed of supercharger I as wellas the increase in the discharge pressure of compressor I1. The speed ofthe supercharger will increase until equilibrium between the forcesacting on bellows 4I and the spring force 43 is attained. Movement ofthe waste gate I9 toward the closed position will also rotate crank 58in a clockwise direction as viewed in the drawings so as to rotateinsulating member 56 downwardly, thereby tending to move contact 52 awayfrom contact-controlling arm 48. If the increase in pressure called forwas small, the4 contact between contact-controlling member 48 andclosing waste gate contact 52 would be broken, stopping motor beforewaste gate I9 vis closed too far. If a large increase in pressure werecalled for, the regulating arm or contact-controlling member 48 wouldfollow closing waste gate contact 52 until the Waste gate was completelyclosed, thus accelerating the supercharger I5 and increasing `thecompressor discharge pressureat the maximum rate possible.

As soon as the desired pressure in box 42 is attained, waste gate motor25 is deenergized so as to stop waste gate. I9 in the proper position tomaintain a new pressure in box 42. -By properly adjusting regulatingmeans 39, the pressure in sealed box 42 will increase rapidly at firstand then slow down just before it reaches the value called for, stoppingat this value with no overshooting or undershooting.

When the critical altitude of the supercharger is reached, governor 63moves arm84 out of engagement with contact 85. A furtherincrease insupercharger speed will cause governor 63 to move contact-controllingarm 84 into engagement with contact 61, thereupon energizing restoringmotor vlill to move member 14 and consequently pivot 49 upwardly so thatcontact-controlling arm 48 engages opening waste gate contact 5I therebycausing motor 25 to be energized to open waste gate I9 with theconsequent reduction in speed of supercharger I5. I1 the speed ofsupercharger I5 is reduced too far, governor 83 will be slowed downsuillciently so that spring 6B will move arm 64 intoengagement withcontact 65, energizing restoring motor 68 so as to move member 'I4 andconsequently pivot 49 downwardly so that contact-controlling arm 48engages closing waste gate contact 52. The follow-up mechanism ccm-f4prising pivotally mounted insulating member 56 will prevent overshootingor undershooting of the speed regulating means above the criticalaltitude.

Although we have disclosed restoring motor 88 as controlling the pivotpoint 49 of contactcontrolling arm 48 while crank 58 operates pivotallymounted insulating member 58, it will be obvious that the follow-upmechanism may include means to move pivot 49 while the restoring motormay control the positions of contacts 5| and 52. Accordingly, in Fig. 2iwe have illustrated a portion of the apparatus in Fig. 1 with thecorresponding parts designated by the same reference numerals showing amodification of our invention. Contact-controlling arm 48 is illustratedas being pivotally mounted at 49 upon a suitable support 80. Pivot 49may be moved vertically and isbiasedin the upper direction as by meansof the spring 8|. Upon movement of waste gate I9, as was mentionedabove, corresponding movement of crank 60 occurs as well as rotation ofshaft 59. We have provided a rotatably mounted cam 82 which engagescontact-controlling arm 48 so as to move pivot 49 Y downwardly inresponse to opening movement of III waste gate I9. Spring 8| 'will ofcourse move pivot 49 upwardly as waste gate I9 is closed and cam 82 isrotated to permit such movement. Cam 82 is rotated by movement of wastegate I9 through operation of a reciprocally mounted rod 83interconnecting crank 84 on shaft 59 and an extension 82 on cam 82. Thescrew 'I3 driven by restoring motor 68 is illustrated as threadedlyengaging an insulating member 85 vertically movable in response torotation of.restoring motor 88 between guides 86. Waste gate openingcontact 5I and waste gate closing contact 52 are mounted on insulatingmember 85. It will be obvious that the arrangement in Fig. 2 willoperate in exactly the same manner as the regulator of Fig. 1 in so faras maintaining constant the discharge pressure below critical altitudeand thereafter maintaining constant the speed of the supercharger.

With the invention described above it is possible to obtain closeautomatic and stable regulation of the turbo-supercharger with improvedapparatus which is simple in construction and reliable in operation.

While we have shown and described particular embodiments of ourinvention, it will be apparent to those skilled in the art that ourinvention is not limited to the particular embodiments shown, but thatchanges and modificaspirit and scope of our invention, and we aim in theappended claims to cover all such changes and modiflcations. y

What we claim as new and desire to secure by Letters Patent of theUnited States is:

l. In combination, a turbosupercharger, valve means for regulating theilow of exhaust gases to the turbine, means including a contactcontrolling member responsive to a predetermined pressure appurtenant toan operating condition of said supercharger for positioning said valvemeans to maintain said predetermined pressure at a substantiallyconstant value over a predetermined range of operation, means for takingcontrol of said supercharger away from said last mentioned means outsidesaid range of 'operation to prevent said supercharger from exceedingA apredetermined speed comprising means responsive to the speed of saidsupercharger, and a motor controlled by said last mentioned means forcontrolling the positioning of said contact controlling member at speedsabove the highest speed within said-range of operation,

2. In combination, a turbosupercharger, valve means for regulating theflow of exhaust gases to the turbine, means including a contactcontrolling member responsive to a predetermined pressure appurtenant toan operating condition of said supercharger for positioning said valvemeans to maintain said predetermined pressure at a substantiallyconstant value over a predetermined range of operation, means for takingcontrol oi said supercharger away from said last mentioned means outsidesaid range of operation to prevent said supercharger from exceeding apredetermined speed, comprising a speed governor driven from saidsupercharger, and a motor controlled by said governor for Controlmeansfor taking control of said supercharger away from said last mentionedmeans outside said range of operation to prevent said supercharger fromexceeding a predetermined speed comprising means responsive to the speedof said supercharger, and a motor controlled by said last mentionedmeans for controlling the position of the pivot pointof said contactcontrolling member at Speeds above the highest speeds within said abovementioned range of operation.

4. In combination, a turbosupercharger, valve means for regulating theflow of exhaust gases to the turbine. means responsive to apredetermined pressure appurtenant to an operating condition of saidsupercharger for positioning said valve means to maintain saidpredetermined pressure at a substantially constant value over apredetermined range of operation including a pivotally mounted contactcontrolling member, means for taking control of said supercharger awayfrom said last mentioned means outside said range of operation toprevent said supercharger from exceeding a predetermined speedcomprising a speed governor including an electric control member, meansfor driving said governor from said supercharger, and a motor controlledby said electric control member for shifting the pivot point of saidcontact controlling member.

5. In combination, a turbosupercharger, a waste gate for regulating thenow of exhaust gases to the turbine. a motor for positioning said wastegate means responsive to a predetermined pressure appurtenant to anoperating condition of said supercharger for controlling said motor toposition said waste gate and maintain said predetermined pressure at asubstantially constant value over a predetermined range of operation,including a Contact controlling member, means for pivotally mountingsaid member, a waste gate opening contact adapted to be engaged by saidcontact controlling member to energize said motor to open said wastegate upon 'an increase in pressure above said predetermined pressure, awaste gate closing contact adapted to be engaged by said contactcontrolling member to energize said motor to close said waste gate upona decrease in pressure below said predetermined pressure, means fortaking control of said supercharger away from said nrst mentioned meansoutside said range of operation to prevent said supercharger fromexceeding a predeterminned speed comprising a speed governor includingan electric control member, means for driving said governor from saidsupercharger, and a restoring motor controlled by said electric controlmember for moving said means for pivotally mounting said member to causesaid contract controlling member to control the waste gate motor.

6. In combination, a turbosupercharger, a waste gate for regulating theiiow o f exhaust gases to the turbine, a motor for positioning saidwaste gate, means responsive to the supercharger outlet pressure forcontrolling said motor to position said waste gate and maintain saidoutlet pressure at a substantially constant value over a predeterminedrange of operation, `said means including a contact controlling member,means for pivotally mounting said member, a waste gate opening contactadapted to be engaged by said contact controlling member to energizesaid motor to open said waste gate upon an increase in said carburetorinlet pressure, a waste gate closing contact adapted to be engaged bysaid contact controlling member to energize said motor to close saidwaste gate upon a decrease in said outlet pressure, means for takingcontrol of said supercharger away from saidrst mentioned means outsidesaid range of operation to prevent said supercharger from exceeding apredetermined speed comprising a speed governor including an electriccontrol member, means for driving said governor from said supercharger,and a restoring motor controlled by said electric control member formoving said means for pivotally mounting said member to cause saidcontact controlling member to control said motor `for positioning saidwaste gate.

'7. In combination, a turbosupercharger, a waste gate for regulating theflow of exhaust gases to the turbine, a motor for positioning said wastegate, means responsive to a predetermined pressure appurtenant to anoperating condition of said supercharger for controlling said motor toposition said waste gate and maintain said predetermined pressure at asubstantially constant value over a predetermined range of operationincluding a contact controlling member, means for pivotally mountingsaid member, a waste gate opening contact adapted to be engaged by saidconjtact controlling member to energize said motor to open said wastegate upon an increase in pressure abovesaid predetermined pressure, awaste gate closing contact adapted to be engaged by said contactcontrolling member lto energize said motor to close said waste gate upona decrease in pressure below said predetermined pressure, means fortaking control of said supercharger -away from said first mentionedmeans outside said range of operation to prevent said supercharger fromexceeding a predetermined speed comprising a speed governor including anelectric control member, means for driving said governor from saidsupercharger, a restoring motor controlled by said electric controlmember for moving said means for pivotally mounting said member to causesaid contact controlling member to control the waste gate motor,and'stabilizing means for moving said Waste gate closing and openingcontacts in response to waste gate position.

8. In combination, a turbosupercharger, a Waste gatg for regulating theflow of exhaust gases to the turbine, a motor for positioning said wastegate, means responsive to the supercharger discharge pressure forcontrolling said motor to position said Waste gate and maintain saiddischarge pressure at a substantially constant value over apredetermined range of operation, said means including a contactcontrolling member, means for pivotally mounting said member, a wastegate opening Contact adapted to be engaged by said contact controllingmember to energize said motor to open said Waste gate upon an increasein said discharge pressure, a waste gate closing contact adapted to beengaged by said contact controlling member to energize said motor toclose said waste gate upon a decrease in said carburetor inlet pressure,means for taking control of said supercliarger away from said firstmentioned means outside said range of operation to prevent saidsupercharger from exceeding a predetermined speed comprising a speedgovernor including an electric control member, means for driving saidgovernor from said supei'cliarger, a restoring motor controlled by saidelectric control member for moving said means for pivotally mountingsaid member to cause said contact controlling member to control saidmotor for positioning said waste gate, and stabilizing means for movingsaid waste gate closing and opening contacts in response to waste gateposition.

motor to position said waste gate and maintain said pressure at asubstantially constant value over a predetermined range of operationincluding a contact controlling member, means for pivotally mountingsaid member, a waste gate opening Contact adapted to be engaged by saidcontact controlling member to energize said motor to open said Wastegate upon an increase in said discharge pressure, a waste gate closingcontact adapted to be engaged by said Contact controlling member toenergize said motor to close said waste gate upon a decrease in saiddischarge pressure, means for taking control of said supercharger awayfrom said rst mentioned means outside said range of operation to preventsaid supercharger from exceeding a predetermined speed comprising aspeed governor including an electric control member, means for drivingsaid governor from said supercharger, and a restorgases to the turbine,a motor for positioning said waste gate, means responsive to thesupercharger discharge pressure for controlling said motor to positionsaid waste gate and maintain said pressure at a substantially constantvalue over a predetermined range of operation including a contactcontrolling member, means for pivotally mounting said member, a wastegate opening contact adapted to be engaged by said contact controllingmember to energize said motor to open said waste gate upon an increasein said discharge pressure, a waste gate closing contact adapted to beengaged by said contact controlling member to energize said motor toclose said Waste gate upon a decrease in said discharge pressure, meansfor taking control of said supercharger away from said first mentionedmeans outside said range of operation to prevent said supercharger fromexceeding a predetermined speed comprising a speed governor including anelectric control member, means for driving said governor from saidsupercharger, a restoring motor controlled by said electric controlmember for moving said waste gate opening and closing contacts, andstabilizing means comprising means for moving said means for pivotallymounting said member in response to waste gate position,

l1. A control mechanism for turbosupercliargers comprising a controlmotor, an electric circuit for the motor including a contact controllingmember, a variable iulcrum for the member, a pressure responsive devicepivotally connected to the member, means cooperatively associated withthe device to limit its operating range, and means including a speedgovernor and electric motor means controlled by the speed governor forvarying said fulcrum outside said operating range.

12a A governing mechanism comprising a contact controlling member, afulcrum supporting the member, a fluid pressure responsive deviceconnected to the member, adjustable means limiting the operating rangeof the iiuid responsive 5 device, and other means for actuating saidmeming motor controlled by said electric control A member for movingsaid waste gate opening and closing contacts.

10. In combination, a turbosupercharger, a waste gate for regulating therloW of exhaust ber outside the operating range of the fluid re-Asponsive device, said other means comprising a motor for positioningsaid fulcrum and a speed responsive device for controlling the motor.

MARTIN A. EDWARDS. MARTIN LEVINE.

